385 million years old fossilized Scottish fish were sexual intercouse pioneers, says palaeontologists

Australian palaeontologists have found sexual intercourse was pioneered by fish, about 385 million years ago in Scotland. The world’s first ever copulating couple did it sideways in Scotland. The fish had two miniature arm-like structurs branching off its tail, which the male used to grip onto the female of the species during copulation. Flinders University’s John Long says it’s not every day you discover something really big in science. Professor Long told journalists says sexual intercourse evolved in our earliest vertebrate ancestors, armoured fish called placoderms, about 385 million years ago, he says. He and colleagues reveal everything they know about Microbrachius dicki’s sex life, with pictures, in the journal Nature.

“Placoderms were once thought to be a dead-end group with no live relatives, but recent studies show that our own evolution is deeply rooted in placoderms and that many of the features we have – such as jaws, teeth and paired limbs – first originated with this group of fishes,” Dr Long said. This new finding, he added, showed “they gave us the intimate act of sexual intercourse as well”. Palaeobiologist from Britain’s Oxford University Matt Friedman described the findings as “nothing short of remarkable” and said they suggested much more could be learned from the fossilised fish.

Flinders University’s Dr Long, whose study was published in the journal Nature, discovered the ancient fish’s mating abilities when he stumbled across a single fossil bone in the collections of the University of Technology in Tallinn, Estonia, last year. The specimens demonstrate the first use of internal fertilisation and copulation as a reproductive strategy known in the fossil record. Measuring about eight centimetres in length, Microbrachius lived in ancient lake habitats in Scotland, as well as parts of Estonia and China.

Dr Long explained “Microbrachius” meant little arms, but said scientists have been baffled for centuries by what these bony paired arms were actually there for. “We’ve solved this great mystery,” he said.